review (S) for 6926979: should simplify catch_inline_exception

[Christian Thalinger]

On 02/19/10 10:10 PM, Tom Rodriguez wrote:
> http://cr.openjdk.java.net/~never/6926979
> 
> 6926979: should simplify catch_inline_exception
> Reviewed-by:
> 
> This is the follow on fix to 6877221 that I'm proposing for hs18.
> That fix patched over some uncommon trap conditions that could result
> in unneeded uncommon traps during exception dispatch.  This fix
> rewrites the exception paths to take advantage of the fast subtype
> checks to handle more cases inline and removes the use of the uncommon
> trap that used Reason_unhandled/Action_none to deal with unloaded
> classes or classes with subtypes.  Instead we emit full subtype checks
> for catch classes with subclass and allow catch_call_exceptions to
> emit a Reason_unloaded exception handler for unloaded catch classes.
> This way we won't uncommon trap unless we really need to and in that
> case we'll throw out the code and recompile.
> 
> src/share/vm/opto/doCall.cpp
> src/share/vm/opto/parse.hpp
> src/share/vm/opto/parse1.cpp

I think this looks good.  What about the removed comment that says:

!     // %%% Now that subclass checking is very fast, we need to rewrite
!     // this section and remove the option "DeutschShiffmanExceptions".

Do we still need this option?

-- Christian